Treatment of cellulosic fabrics and the fabrics thereby obtained



United States Patent Ofi ice 3,109,695 Patented Nov. 5, 1963 3,109,695TREATMENT OF CELLULOSIC FABRICS AND THE FABRICS THEREBY OBTAINED JohnLeslie Gardon, Levittown, Pa., assignor to Rohm & Haas Company,Philadelphia, Pa., a corporation of Delaware No Drawing. Filed Sept. 27,1960, Ser. No. 58,639

12 Claims. (Cl. 8-116.4)

This invention relates to the treatment of cellulosic fabrics, such asthose of cotton and regenerated cellulose rayon, for the purpose ofimparting to them increased resilience, improved recovery from creasing,wrinkling, and other deformations, and the characteristic of havingreduced shrinkage on washing so that partial or complete dimensionalstabilization may be effected. The invention also embraces the treatedfabrics obtained.

In accordance with the present invention, it has been found thatcellulosic fabrics, woven, knitted, or otherwise formed, have reducedshrinkage on washing and acquire resistance to creasing and crushingwhen they are treated with dihydroxyacetone of the formula HOCH COCH OH.The extent of modification by means of this compound may be controlledby variation in the proportion of the dihydroxyacetone and by variationin the amount of catalyst employed during the treatment therewith.

The treatment with dihydroxyacetone may be effected most advantageouslyby means of aqueous solutions thereof in which the dihydroxyacetone isdissolved at a concentration which may vary from 2 to 25% by weight.Preferably, the concentration is from 5 to 15% to obtain the maximumbenefits in crease proofing and the like.

The treatment with dihydroxyacetone may be carried out in the presenceof a catalyst. Suitable catalysts are acids or acidic salts, such asoxalic acid, potassium persulfate, potassium bisulfate, magnesiumchloride, ammonium chloride, zinc nitrate, zinc fluoborate, zincperchlorate, and amine salts, such as the hydrochloride or sulfate oftriethylamine, pyridine, morpholine, and 2- methyl-Z-aminopropanol-l.Oxalic acid is a preferred catalyst with relatively little tendency tocause discoloration requiring bleaching.

Conveniently, the amount of catalyst may vary from about 0.1 to 5% andis preferably in the range of 1.0 to 2% concentration in the aqueoussolution of dihydroxy- 'acetone.

The catalyzed solution of dihydroxyacetone is compatible with solutionsor dispersions of most of the common textile finishing agents, such assynthetic polymer latices and aminoplast resins or precondensates, sothat they may be applied with the dihydroxyacetone to produce changes inthe hand or other properties of the fabric.

The aqueous solution containing dihydroxyacetone and 'catalyst may beapplied to the fabric in any suitable manner such as spraying orimpregnation. In general, it is preferable to use some method ofimpregnation. With piece goods, this is conveniently carried out withthe various machines used for treating fabrics in open width, such aspads or jigs. However, it is not required that the impregnation becarried out in open width, and the fabric may be handled in any form. intreating garments or other articles made from cellulosic fabrics, theimpregnation may be carried out in a tumble wheel, laundry machine, orother suitable equipment. After application of the solution, it isdesirable to remove the excess solution by squeezing the fabric betweenrollers, or by shaking or centrifuging it, in order to insure a moreeven treatment. The fabric treated with solution may be dried, such asby a=ir-drying at normal room temperature or by heating in a drying ovenat temperatures of 60 C. and up. The drying and curing operations arepreferably done with the fabric open and flat, so that it will have asmooth and even appearance when finished. In a preferred embodiment; theimpregnated fabric, immediately after impregnation and withoutpreliminary low-temperature drying, is carried in open width by a tenterframe through a curing oven where it is subjected to temperatures ofabout C. to about 2.00 C. or higher for a period of time ranging fromabout one-half minute to about one-half hour or more, the shorter periodbeing employed at the higher temperature and vice versa. Entirelysatisfactory results are obtained by heating for 3 to 5 minutes at aboutC. This curing operation not only dries the impregnated fabric butapparently causes a reaction between the dihydroxyacetone and thehydroxyl groups of the cellulose. The precise reaction is not known. Itis theorized that the two hydroxyl groups of the dihydroxyacetone mayethen'fy hydroxyl groups of the same or different molecules ofcellulose, but it is also thought that the carbonyl group may take partin the reaction so that a single molecular residue of dihydroxyacetoneis connected at three points to from one to three cellulose molecules.It is not intended, however, that the present invention be limited tothis theory of operation.

The treated fabrics exhibit a high degree of crush resistance and creaserecovery with little or no change in the hand or feel of the fabric. Inaddition, the treated fabrics have the important advantage that they donot retain chlorine, so that the use of bleaching agents containingchlorine does not cause deterioration either by way of discoloration orloss in tensile strength even when the treated fabrics which have beenbleached are subjected to ironing temperatures. The treated fabrics arealso resistant to shrinkage during laundering, and the treatment is verypermanent towards laundering, dry-cleaning, and other procedures forcleaning textile fabrics. The treatment of the present invention usingdihydroxyacetone as the sole cross-linking or crease-proofing agentprovides a finish that is more stable to hydrolysis in acids andalkalies than the usual nitrogenous or aminoplast finishes. Any colorintroduced by the treatment is readily removable by reducing agents,such as sodium borohydride and sodium formaldehyde sulfoxylate.

The following examples illustrate the present invention, and the partsand percentages therein are by weight unless otherwise noted. Thecrease-recovery values given below were determined by the ShirleyInstitute procedure (British Standards Handbook No. 11, 1949 ed., page128), in the warp direction.

Example 1 A sample of cotton printcloth was saturated with an aqueoussolution containing 16% dihydroxyacetone and 0.8% zinc perchlorate. Itwas then put into an oven at 150 C. and baked for 15 minutes. A controltreated with water was similarly prepared. After being conditioned, thesamples had the following crease-recovery values:

Crease-recovery angle, degrees Water control 71 Dihydroxyacetone 141 Thedihydroxyacetone-treated fabric was insoluble in cuprammonium hydroxidewhile the control dissolved readily.

The durability of the treatment was shown by the following tests.Samples of the dihydroxyacetone-treated fabric were extracted (1) inboiling water for one hour, (2) in 0.1 N HCl at 80 C. for one hour, and(3) in 0.1 N NaOH for 24 hours at 20 C. The extracted samples were stillinsoluble in cuprammonium hydroxide and had good crease-recovery, asshown by the following data:

Degrees Water extr on 132 HCl extr on 125 NaOH extr on 123 Example 2Example 3 A sample of cotton printcloth was saturated with a 16% aqueoussolution of dihydroxyacetone containing 0.4% NH Cl as the catalyst. Itwas cured in an oven at 150 C. for 15 minutes. After being conditioned,the sample had a creasearecovery angle of 136.

Example 4 A sample of cotton printcloth was treated with a solutioncontaining 10% of dihydroxyacetone, 1% of oxalic acid, and 4% of apartially condensed urea-formaldehyde resin. The treated fabric wascured for 15 minutes at 150 C. After being conditioned, it had astiffer, firmer, more resilient hand and a crease-recovery of 137.

Example 5 A sample of cotton printcloth was treated with a solutioncontaining a mixture of 5% dihydroxyacetone and 5%dimethylol'N,N'-ethyleneurea with 1% oxalic acid as a catalyst. Theapplication was made on a textile pad and the impregnated fabric wasbaked for minutes (2. at 150 C. After the fabric was conditioned, itscreaserecovery angle was 139.

I claim:

1. The process comprising impregnating a cellulosic fabric with anaqueous solution of dihydroxyacetone and an acidic catalyst and heatingthe impregnated fabric at a temperature of about to 200 (3., whereby thecrease resistance of the fabric is increased.

2. A process as defined in claim 1 in which the fabric is cotton.

3. A process as defined in is rayon.

4. The process comprising impregnating a cellulosic fabric with anaqueous solution containing 2 to 25% by weight of dihydroxyacetone and0.1 to 5% of an acidic catalyst and heating the impregnated fabric at atemperature of about 110 to 200 C.

5. A process as defined in claim 4 in which the fabric is cotton.

6. A process as defined in claim 4 in which the fabric is rayon.

7. The process comprising impregnating a oellulosic fabric with anaqueous solution containing 2 to 25% by weight of dihydroxyacetone and0.1 to 5% of oxalic acid as a catalyst, and heating the impregnatedfabric at a temperature of about 110 to 200 C.

8. A process according to claim 7 in which the fabric is cotton.

9. A process according to claim 7 in which the fabric is rayon.

10. A cellulosic fabric having improved crease resistance obtained bythe process claim 1.

11. A cotton fabric having improved crease resistance obtained by theprocess of claim 8.

12. A regenerated cellulosic fabric having improved crease resistanceobtained by the process of claim 9.

claim 1 in which the fabric References Cited in the file of this patentUNITED STATES PATENTS

1. THE PROCESS COMPRISING IMPREGNATING A CELLULOSIC FABRIC WITH AN AQUEOUS SOLUTION OF DIHYDROXYACETONE AND AN ACIDIC CATALYST AND HEATING THE IMPREGNATED FABRIC AT A TEMPERATURE OF ABUT 110* TO 200*C., WHEREBY THE CREASE RESISTANCE OF THE FABRIC IS INCREASED. 